Electronic Configuration of Early Transition Metals

The metals forming interstitial carbides are the early -block transition elements. In these elements, the d shell is an inner shell and is only partially filled. The valence (bonding) electrons include not only the s electrons of the outermost shell but also the d electrons of that unfilled d shell. The bonding characteristics of these 3 -block elements are quite sensitive to the number and arrangement of the d electrons present. 

The electronic configuration is shown in Table 3.1. One should note that the d shell is never more than half-full (a full d shell having 10 electrons). 

The three metals of the fourth period (Ti, V, Cr) have a inner subshell which is filled with a gradually increasing number of electrons while the outermost subshell As is virtually the same. Thqr are known as 3d transition elements. 

In the case of the three metals of tiie fifth period (Zr, Nb, Mo), it is the inner subshell Ad that is gradually filled with an increasing number of electrons the 4/ shell remains empty. They are known as Ad transition elements. 

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Table 3.1 Electronic Configuration of Early Transition Metals i...

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